The overarching goal of this project is to evaluate the application of bone marrow stromal stem cell transplantation for therapy of the gangliosidoses using well characterized, authentic feline models of the human gangliosidoses. We will undertake a comprehensive characterization of feline bone marrow stromal cells (MSC) in vitro, with emphasis on their capacity to differentiate to neurons and glial of the central nervous system (CNS). We have isolated and partially characterized feline marrow stromal cells (MSC) based on morphology, in vitro growth traits, cell surface antigens and capacity to differentiate to cells of a neuronal phenotype. We will continue characterization of feline MSC to determine if significant species differences exist which may influence plasticity and function in vivo. We will transplant feline MSC to analyze their distribution and differentiation in the central nervous system and non-CNS organs. Feline MSC will be labeled with a receptor gene, then injected into normal feline subjects and analyzed at various time points to assess the neuronal and glial lineages derived from such cells. MSC will be injected intra cerebrally, intraventricularly or intravenously into 8-12 week old cats or intracranially and intra peritoneally into cat fetuses. Trafficking of MSC injected in utero or postnatally will be monitored in brain, bone marrow and a variety of parenchymatous organs. We will transplant normal or vector corrected MSC into cats affected with GM1 gangliosidosis to assess therapeutic potential. Therapeutic transplantation of feline MSC will include: a) Normal MSC derived from parent or sibling donors will be labeled with a reporter gene, injected in utero into cat fetuses, and evaluated after birth for fate and distribution of labeled cells and amelioration of disease; b) Autologous MSC harvested postnatally from cats with GM1 gangliosidosis will be transfected with a lentiviral vector bearing a lysosomal beta-galactosidase cDNA to correct their enzymatic deficiency and re-implanted into brain or injected intravenously. Kittens with the gangliosidoses will be evaluated for progression of neurological, hepatic and thymic disease. Mechanisms by which stem cell transplantation may alter the course of the gangliosidoses will be studied.